An error-avoidance pathway for the correction of mispaired bases has been identified in E. coli. According to the proposed mechanism, discrimination between the 'correct" parental DNA strand and the "error-containing" daughter strand depends upon DNA methylation. The E. coli genes dam, mutH, mutL, mutS and uvrD/E are thought to be involved. This DNA repair system may contribute to the high level of replicational fidelity observed in living organisms. Recent evidence suggest that the mismatch repair pathway in inducible and that mismatch repair can avoid indirect mutagenesis due to the induction of SOS repair, and misincorporation errors due to miscoding lesions.